A 2.0-kg ball rolls to the right at 3.0 m/s. A 4.0-kg ball rolls to the left at 2.0 m/s . What is the momentum of the system after a head-on collision of the two balls?

Final momentum after a head on collision is -2kgm/s

Explanation:

         One ball moves to the right and the other moves opposite  and momentum is a vector quantity so that considering the direction

Initial momenta are        P₁=2x3=6kgm/s        P₂=4x(-2)=-8kgm/s      

Final momentum is the vector sum of P(final)= 6-8= -2 kgm/s

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.